In recent years, with the expansion of internet service, the role of a data center in which a server that perform an information process and a network apparatus are gathered in one place increases. Further, with the increase of the amount of information processed by the data center, the electric power consumed by the data center increases.
In particular, the electronic apparatus is accommodated in the data center and an air-conditioning equipment for cooling the electronic apparatus consumes a large percentage of the total electric power consumed by the data center. In the electronic apparatus, a plurality of electronic components including a heat-producing element such as a central processing unit (CPU), a Multi-chip Module (MCM), or the like are used. Such air-conditioning equipment consumes about one half of the total electric power consumed by the data center.
Accordingly, it is requested to reduce the electric power used for air conditioning in the data center. For this purpose, a method in which heat exhausted from a rack main body of an electronic apparatus enclosure device for accommodating the electronic apparatus is directly transported to the outside of the building and discharged to the outside air without using the air-conditioning equipment is used on a trial basis. By adopting this method, the electric power used for air conditioning in the data center can be reduced.
Further, as a method for transporting the heat exhausted from the rack main body of the electronic apparatus enclosure device to the outside of the building, a method using a phase change phenomenon of refrigerant is known besides a method in which cold water supplied from the outside is circulated by a pump.
In the method using the phase change phenomenon of refrigerant, refrigerant is circulated by repeating an evaporation phenomenon which occurs when a phase of refrigerant changes from liquid to vapor and a condensation phenomenon which occurs when a phase of refrigerant changes from vapor to liquid (this repeating motion is also called an evaporation-condensation cycle). In the method using the phase change phenomenon of refrigerant, refrigerant is naturally circulated without using an external driving force such as a pump or the like and a large amount of heat transfer can be realized because latent heat is used. Therefore, it is expected to contribute to the reduction of the electric power used for air conditioning in the data center.
The above-mentioned method using the phase change phenomenon of refrigerant (it is also called a refrigerant natural circulation cooling method) is disclosed in for example, patent literature 1.
In the refrigerant natural circulation cooling method disclosed in patent literature 1, heat exhausted from the electronic apparatus mounted in a server rack 26 is transported to an evaporator 34 mounted on a rack back face via refrigerant. The heat that is exhausted from the electronic apparatus and transported to the evaporator 34 is consumed as the vaporization heat when the phase of the refrigerant changes from liquid to vapor and the heat is transported to cooling towers 38 and 76 located outside the building. As a result, the temperature of the server room can be reduced. Further, a flexible vapor pipe 78 and a flexible liquid pipe 80 are connected to the evaporator 34. The vapor pipe 78 is provided to transport vapor. The liquid pipe 80 is provided to transport liquid.